Re: [PATCH 5/8] drm/i915: Add second slice l3 remapping

Bell, Bryan J
2013-09-17T19:08:27Z

> -----Original Message-----
> From: Ville Syrjälä [mailto:ville.syrjala@linux.intel.com]
> Sent: Tuesday, September 17, 2013 12:02 PM
> To: Bell, Bryan J
> Cc: Ben Widawsky; Widawsky, Benjamin; intel-gfx@lists.freedesktop.org; Venkatesh, Vishnu
> Subject: Re: [Intel-gfx] [PATCH 5/8] drm/i915: Add second slice l3 remapping
>
> On Tue, Sep 17, 2013 at 06:51:31PM +0000, Bell, Bryan J wrote:
> > >> > + spin_lock_irqsave(&dev_priv->irq_lock, flags);
> > >> > + ilk_enable_gt_irq(dev_priv, GT_PARITY_ERROR);
> > >>
> > >> Is it actually safe to enable the second slice irq when there's no
> > >> second slice? This docs say it's just "reserved", but no mention
> > >> whether it RO or could there be side effects.
> >
> > >Tests on my machine appear to work. But I don't know for certain. Bryan, could you answer this?
> >
> > On the Windows driver we enable the IRQ on all HSW skus and haven't seen any issues.
>
> This code would enable it for IVB too. Any data on that?

No data on IVB, I recommend against enabling it on IVB.

FYI: My understanding is that L3 DPF code and or interrupts should be disabled on VLV.
VLV does not support dynamic L3 row replacement.

> >
> > -----Original Message-----
> > From: Ben Widawsky [mailto:ben@bwidawsk.net]
> > Sent: Tuesday, September 17, 2013 11:46 AM
> > To: Ville Syrjälä; Bell, Bryan J
> > Cc: Widawsky, Benjamin; intel-gfx@lists.freedesktop.org; Venkatesh,
> > Vishnu
> > Subject: Re: [Intel-gfx] [PATCH 5/8] drm/i915: Add second slice l3
> > remapping
> >
> > On Fri, Sep 13, 2013 at 12:38:01PM +0300, Ville Syrjälä wrote:
> > > On Thu, Sep 12, 2013 at 10:28:31PM -0700, Ben Widawsky wrote:
> > > > Certain HSW SKUs have a second bank of L3. This L3 remapping has a
> > > > separate register set, and interrupt from the first "slice". A
> > > > slice is simply a term to define some subset of the GPU's l3
> > > > cache. This patch implements both the interrupt handler, and
> > > > ability to communicate with userspace about this second slice.
> > > >
> > > > Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> > > > ---
> > > > drivers/gpu/drm/i915/i915_drv.h | 9 ++--
> > > > drivers/gpu/drm/i915/i915_gem.c | 26 ++++++----
> > > > drivers/gpu/drm/i915/i915_irq.c | 84 +++++++++++++++++++++------------
> > > > drivers/gpu/drm/i915/i915_reg.h | 6 +++
> > > > drivers/gpu/drm/i915/i915_sysfs.c | 34 ++++++++++---
> > > > drivers/gpu/drm/i915/intel_ringbuffer.c | 6 +--
> > > > include/uapi/drm/i915_drm.h | 8 ++--
> > > > 7 files changed, 115 insertions(+), 58 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/i915_drv.h
> > > > b/drivers/gpu/drm/i915/i915_drv.h index 81ba5bb..eb90461 100644
> > > > --- a/drivers/gpu/drm/i915/i915_drv.h
> > > > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > > > @@ -918,9 +918,11 @@ struct i915_ums_state {
> > > > int mm_suspended;
> > > > };
> > > >
> > > > +#define MAX_L3_SLICES 2
> > > > struct intel_l3_parity {
> > > > - u32 *remap_info;
> > > > + u32 *remap_info[MAX_L3_SLICES];
> > > > struct work_struct error_work;
> > > > + int which_slice;
> > > > };
> > > >
> > > > struct i915_gem_mm {
> > > > @@ -1686,7 +1688,8 @@ struct drm_i915_file_private {
> > > >
> > > > #define HAS_FORCE_WAKE(dev) (INTEL_INFO(dev)->has_force_wake)
> > > >
> > > > -#define HAS_L3_GPU_CACHE(dev) (IS_IVYBRIDGE(dev) ||
> > > > IS_HASWELL(dev))
> > > > +#define HAS_L3_GPU_CACHE(dev) (INTEL_INFO(dev)->gen >= 7) #define
> > > > +NUM_L3_SLICES(dev) (IS_HSW_GT3(dev) ? 2 : HAS_L3_GPU_CACHE(dev))
> > > >
> > > > #define GT_FREQUENCY_MULTIPLIER 50
> > > >
> > > > @@ -1947,7 +1950,7 @@ bool i915_gem_clflush_object(struct
> > > > drm_i915_gem_object *obj, bool force); int __must_check
> > > > i915_gem_object_finish_gpu(struct drm_i915_gem_object *obj); int
> > > > __must_check i915_gem_init(struct drm_device *dev); int
> > > > __must_check i915_gem_init_hw(struct drm_device *dev); -void
> > > > i915_gem_l3_remap(struct drm_device *dev);
> > > > +void i915_gem_l3_remap(struct drm_device *dev, int slice);
> > > > void i915_gem_init_swizzling(struct drm_device *dev); void
> > > > i915_gem_cleanup_ringbuffer(struct drm_device *dev); int
> > > > __must_check i915_gpu_idle(struct drm_device *dev); diff --git
> > > > a/drivers/gpu/drm/i915/i915_gem.c
> > > > b/drivers/gpu/drm/i915/i915_gem.c index 5b510a3..b11f7d6c 100644
> > > > --- a/drivers/gpu/drm/i915/i915_gem.c
> > > > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > > > @@ -4256,16 +4256,21 @@ i915_gem_idle(struct drm_device *dev)
> > > > return 0;
> > > > }
> > > >
> > > > -void i915_gem_l3_remap(struct drm_device *dev)
> > > > +void i915_gem_l3_remap(struct drm_device *dev, int slice)
> > > > {
> > > > drm_i915_private_t *dev_priv = dev->dev_private;
> > > > + u32 reg_base = GEN7_L3LOG_BASE + (slice * 0x200);
> > > > + u32 *remap_info = dev_priv->l3_parity.remap_info[slice];
> > > > u32 misccpctl;
> > > > int i;
> > > >
> > > > if (!HAS_L3_GPU_CACHE(dev))
> > > > return;
> > > >
> > > > - if (!dev_priv->l3_parity.remap_info)
> > > > + if (NUM_L3_SLICES(dev) < 2 && slice)
> > > > + return;
> > >
> > > This check is redundant as we should never populate
> > > l3_parity.remap_info[1] when there's no second slice.
> > >
> >
> > Got it. Smashed the early exit check together while at it.
> >
> > > > +
> > > > + if (!remap_info)
> > > > return;
> > > >
> > > > misccpctl = I915_READ(GEN7_MISCCPCTL); @@ -4273,17 +4278,17 @@
> > > > void i915_gem_l3_remap(struct drm_device *dev)
> > > > POSTING_READ(GEN7_MISCCPCTL);
> > > >
> > > > for (i = 0; i < GEN7_L3LOG_SIZE; i += 4) {
> > > > - u32 remap = I915_READ(GEN7_L3LOG_BASE + i);
> > > > - if (remap && remap != dev_priv->l3_parity.remap_info[i/4])
> > > > + u32 remap = I915_READ(reg_base + i);
> > > > + if (remap && remap != remap_info[i/4])
> > > > DRM_DEBUG("0x%x was already programmed to %x\n",
> > > > - GEN7_L3LOG_BASE + i, remap);
> > > > - if (remap && !dev_priv->l3_parity.remap_info[i/4])
> > > > + reg_base + i, remap);
> > > > + if (remap && !remap_info[i/4])
> > > > DRM_DEBUG_DRIVER("Clearing remapped register\n");
> > > > - I915_WRITE(GEN7_L3LOG_BASE + i, dev_priv->l3_parity.remap_info[i/4]);
> > > > + I915_WRITE(reg_base + i, remap_info[i/4]);
> > > > }
> > > >
> > > > /* Make sure all the writes land before disabling dop clock gating */
> > > > - POSTING_READ(GEN7_L3LOG_BASE);
> > > > + POSTING_READ(reg_base);
> > > >
> > > > I915_WRITE(GEN7_MISCCPCTL, misccpctl); } @@ -4377,7 +4382,7 @@
> > > > int i915_gem_init_hw(struct drm_device *dev) {
> > > > drm_i915_private_t *dev_priv = dev->dev_private;
> > > > - int ret;
> > > > + int ret, i;
> > > >
> > > > if (INTEL_INFO(dev)->gen < 6 && !intel_enable_gtt())
> > > > return -EIO;
> > > > @@ -4396,7 +4401,8 @@ i915_gem_init_hw(struct drm_device *dev)
> > > > I915_WRITE(GEN7_MSG_CTL, temp);
> > > > }
> > > >
> > > > - i915_gem_l3_remap(dev);
> > > > + for (i = 0; i < NUM_L3_SLICES(dev); i++)
> > > > + i915_gem_l3_remap(dev, i);
> > > >
> > > > i915_gem_init_swizzling(dev);
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/i915_irq.c
> > > > b/drivers/gpu/drm/i915/i915_irq.c index 13d26cf..62cdf05 100644
> > > > --- a/drivers/gpu/drm/i915/i915_irq.c
> > > > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > > > @@ -882,9 +882,10 @@ static void ivybridge_parity_work(struct work_struct *work)
> > > > drm_i915_private_t *dev_priv = container_of(work, drm_i915_private_t,
> > > > l3_parity.error_work);
> > > > u32 error_status, row, bank, subbank;
> > > > - char *parity_event[5];
> > > > + char *parity_event[6];
> > > > uint32_t misccpctl;
> > > > unsigned long flags;
> > > > + uint8_t slice = 0;
> > > >
> > > > /* We must turn off DOP level clock gating to access the L3 registers.
> > > > * In order to prevent a get/put style interface, acquire struct
> > > > mutex @@ -892,45 +893,63 @@ static void ivybridge_parity_work(struct work_struct *work)
> > > > */
> > > > mutex_lock(&dev_priv->dev->struct_mutex);
> > > >
> > > > + /* If we've screwed up tracking, just let the interrupt fire again */
> > > > + if (WARN_ON(!dev_priv->l3_parity.which_slice))
> > > > + goto out;
> > > > +
> > > > misccpctl = I915_READ(GEN7_MISCCPCTL);
> > > > I915_WRITE(GEN7_MISCCPCTL, misccpctl & ~GEN7_DOP_CLOCK_GATE_ENABLE);
> > > > POSTING_READ(GEN7_MISCCPCTL);
> > > >
> > > > - error_status = I915_READ(GEN7_L3CDERRST1);
> > > > - row = GEN7_PARITY_ERROR_ROW(error_status);
> > > > - bank = GEN7_PARITY_ERROR_BANK(error_status);
> > > > - subbank = GEN7_PARITY_ERROR_SUBBANK(error_status);
> > > > + while ((slice = ffs(dev_priv->l3_parity.which_slice)) != 0) {
> > > > + u32 reg;
> > > >
> > > > - I915_WRITE(GEN7_L3CDERRST1, GEN7_PARITY_ERROR_VALID |
> > > > - GEN7_L3CDERRST1_ENABLE);
> > > > - POSTING_READ(GEN7_L3CDERRST1);
> > > > + if (WARN_ON(slice >= MAX_L3_SLICES))
> > > > + break;
> > >
> > > Could be >= NUM_L3_SLICES(dev) for a bit of extra paranoia. Also we
> > > would fail to clear invalid bits from which_slice in this case, and
> > > thus we'd get the WARN every time the work runs. But I guess this
> > > should never happen in any case so probably not worth worrying about
> > > this too much.
> >
> > Not worth worrying, but I didn't mean to be so noisy. I've fixed this with WARN_ON_ONCE.
> >
> > >
> > > >
> > > > - I915_WRITE(GEN7_MISCCPCTL, misccpctl);
> > > > + dev_priv->l3_parity.which_slice &= ~(1<<slice);
> > > >
> > > > - spin_lock_irqsave(&dev_priv->irq_lock, flags);
> > > > - ilk_enable_gt_irq(dev_priv, GT_RENDER_L3_PARITY_ERROR_INTERRUPT);
> > > > - spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
> > > > + reg = GEN7_L3CDERRST1 + (slice * 0x200);
> > > >
> > > > - mutex_unlock(&dev_priv->dev->struct_mutex);
> > > > + error_status = I915_READ(reg);
> > > > + row = GEN7_PARITY_ERROR_ROW(error_status);
> > > > + bank = GEN7_PARITY_ERROR_BANK(error_status);
> > > > + subbank = GEN7_PARITY_ERROR_SUBBANK(error_status);
> > > > +
> > > > + I915_WRITE(reg, GEN7_PARITY_ERROR_VALID | GEN7_L3CDERRST1_ENABLE);
> > > > + POSTING_READ(reg);
> > > > +
> > > > + parity_event[0] = I915_L3_PARITY_UEVENT "=1";
> > > > + parity_event[1] = kasprintf(GFP_KERNEL, "ROW=%d", row);
> > > > + parity_event[2] = kasprintf(GFP_KERNEL, "BANK=%d", bank);
> > > > + parity_event[3] = kasprintf(GFP_KERNEL, "SUBBANK=%d", subbank);
> > > > + parity_event[4] = kasprintf(GFP_KERNEL, "SLICE=%d", slice);
> > > > + parity_event[5] = NULL;
> > > >
> > > > - parity_event[0] = I915_L3_PARITY_UEVENT "=1";
> > > > - parity_event[1] = kasprintf(GFP_KERNEL, "ROW=%d", row);
> > > > - parity_event[2] = kasprintf(GFP_KERNEL, "BANK=%d", bank);
> > > > - parity_event[3] = kasprintf(GFP_KERNEL, "SUBBANK=%d", subbank);
> > > > - parity_event[4] = NULL;
> > > > + kobject_uevent_env(&dev_priv->dev->primary->kdev.kobj,
> > > > + KOBJ_CHANGE, parity_event);
> > > >
> > > > - kobject_uevent_env(&dev_priv->dev->primary->kdev.kobj,
> > > > - KOBJ_CHANGE, parity_event);
> > > > + DRM_DEBUG("Parity error: Slice = %d, Row = %d, Bank = %d, Sub bank = %d.\n",
> > > > + slice, row, bank, subbank);
> > > >
> > > > - DRM_DEBUG("Parity error: Row = %d, Bank = %d, Sub bank = %d.\n",
> > > > - row, bank, subbank);
> > > > + kfree(parity_event[4]);
> > > > + kfree(parity_event[3]);
> > > > + kfree(parity_event[2]);
> > > > + kfree(parity_event[1]);
> > > > + }
> > > > +
> > > > + I915_WRITE(GEN7_MISCCPCTL, misccpctl);
> > > > +
> > > > +out:
> > > > + WARN_ON(dev_priv->l3_parity.which_slice);
> > >
> > > First I figured the irq could rearm this behind our back, but we
> > > disable the irq until the work is done. So yeah, this is fine.
> > >
> > > > + spin_lock_irqsave(&dev_priv->irq_lock, flags);
> > > > + ilk_enable_gt_irq(dev_priv, GT_PARITY_ERROR);
> > >
> > > Is it actually safe to enable the second slice irq when there's no
> > > second slice? This docs say it's just "reserved", but no mention
> > > whether it RO or could there be side effects.
> >
> > Tests on my machine appear to work. But I don't know for certain. Bryan, could you answer this?
> >
> > >
> > > > + spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
> > > >
> > > > - kfree(parity_event[3]);
> > > > - kfree(parity_event[2]);
> > > > - kfree(parity_event[1]);
> > > > + mutex_unlock(&dev_priv->dev->struct_mutex);
> > > > }
> > > >
> > > > -static void ivybridge_parity_error_irq_handler(struct drm_device
> > > > *dev)
> > > > +static void ivybridge_parity_error_irq_handler(struct drm_device
> > > > +*dev, u32 iir)
> > > > {
> > > > drm_i915_private_t *dev_priv = (drm_i915_private_t *)
> > > > dev->dev_private;
> > > >
> > > > @@ -938,9 +957,12 @@ static void ivybridge_parity_error_irq_handler(struct drm_device *dev)
> > > > return;
> > > >
> > > > spin_lock(&dev_priv->irq_lock);
> > > > - ilk_disable_gt_irq(dev_priv, GT_RENDER_L3_PARITY_ERROR_INTERRUPT);
> > > > + ilk_disable_gt_irq(dev_priv, GT_PARITY_ERROR);
> > > > spin_unlock(&dev_priv->irq_lock);
> > > >
> > > > + iir &= GT_PARITY_ERROR;
> > > > + dev_priv->l3_parity.which_slice =
> > > > + 1 << (iir & GT_RENDER_L3_PARITY_ERROR_INTERRUPT_S1 ? 1 : 0);
> > >
> > > What if both slices report an error at the same time?
> >
> > I was thinking that such an event can not occur, but on rethinking it
> > you are right that it's possible. I really hope this never happens,
> > but it's fixed. Anyway, it should have been |=, not =
> >
> >
> > [snip]
> >
> > I'll resend the patch after Bryan answers the question about both interrupts.
> >
> > --
> > Ben Widawsky, Intel Open Source Technology Center
>
> --
> Ville Syrjälä
> Intel OTC

--Regards
Bryan